Faster and Cheaper: ARM Graviton vs Intel and AMD x86 AWS EC2

Measure, measure, measure, and do the math. It pays.

ARM vs x86 performance

Generally, AWS ARM EC2 instances perform similarly to their x86 equivalents. AWS prices them that way with a bit of favour towards ARM. But they are different architectures, and sometimes, one excels over the other in specific tasks.

I recently switched an EC2 fleet from x86 to ARM as a sense check, expecting similar performance. Occasional experiments allow you to (re)check assumptions if you always measure and have baselines. 

To my surprise, there was a substantial performance difference of approximately 70% for the specific workload on this fleet, i.e. ARM performed 170% throughput of the x86 equivalents for both Intel and AMD instances (see above image).

ARM vs x86 cost

While an impressive improvement, it does not yet account for the price difference. Always watch spot prices, as they can spike and exceed on-demand costs. Sometimes ARM, while having a lower initial cost, can exceed x86 spot prices. However, in this case, the ARM instances cost 75% of the x86 equivalents I used before. 

Savings

In summary, we achieved 2.3x per $ by switching from x86 to ARM when combining the higher throughput and lower cost per instance. The caveat from the post should be clear. Improvements depend entirely on your workload and instance (spot) prices and are not a general rule. It is a reminder that measuring, observing and experimenting with your performance and cost is essential.